The invention relates to a method for operating an internal combustion engine especially of a motor vehicle wherein fuel is injected into the combustion chamber in at least two modes of operation and wherein a switchover between the two modes of operation is made in dependence upon a desired mode of operation. Likewise, the invention relates to an internal combustion engine, especially for a motor vehicle, having a combustion chamber into which fuel can be injected in at least two modes of operation and having a control apparatus with which a switchover between the modes of operation can be made in dependence upon a desired mode of operation.
A method of this kind and an internal combustion engine of this kind are known, for example, from a so-called gasoline direct injection. There, fuel is injected into the combustion chamber in a homogeneous operation during the induction phase or in a stratified operation during the compression phase. The homogeneous operation is preferably provided for the full-load operation of the engine; whereas, the stratified operation is suitable for idle operation and part-load operation. For example, in a direct-injection engine of this kind, a switchover between the above-mentioned modes of operation takes place in dependence upon the wanted desired mode of operation.
This desired mode of operation results, inter alia, from the particular operating state of the engine. Thus, the homogeneous operation can be purposeful, for example, for a cold start of the engine. In contrast thereto, it is possible that, for example, the stratified operation is preferred when there is a defect. The correct desired mode of operation must be determined for the particular time point from these modes of operation of the engine.
The object of the invention is to provide a method for operating an internal combustion engine with which a flexible but nonetheless effective determination of the desired mode of operation is possible.
This object is achieved with a method of the above-mentioned type in accordance with the invention in that the desired mode of operation is determined from a plurality of operating mode requests. In an engine of the above-mentioned type, the task is solved in accordance with the invention in that the desired operating mode can be determined by the control apparatus from a plurality of operating mode requests.
Specific functions in the control apparatus are assigned to the various possible operating states of the engine. These functions can trigger operating mode requests. Like functions can be bundled together and be provided with a common operating mode request. An operating mode command can be limited to a specific wanted mode of operation but can also include several modes of operation. The operating mode requests of all functions of the engine are processed by the control apparatus. The control apparatus determines the desired mode of operation from these operating mode requests.
In this manner, a decoupling is achieved between the respective functions of the engine and the desired operating mode. This affords the advantage that the programs for the functions can be configured clearly and manageably and especially independently of each other. The functions are brought into connection with the desired operating mode only by the introduction of the operating mode requests corresponding to the functions. In this way, the possibility is provided by the invention to assign the individual functions and therefore the individual operating mode requests to respective individual programs in the control apparatus. These programs can be built up in modular fashion and thereby are simpler and more flexible to produce and to change and, at the same time, the occurrence of defects is less.
In an advantageous configuration of the invention, each of the operating mode requests is assigned a priority and the determination of the desired operating mode is carried out in dependence upon the priorities of the operating mode requirements. In this way, it is possible to weight the various operating mode requests of the engine. Especially operating mode requests which relate to specific operating states or their functions (for example, to the protection of components against destruction or to the emergency operation of the engine) can be provided with a higher priority than, for example, the cold start of the engine. This weighting can again be changed rapidly and with flexibility because of the modular-like configuration.
Preferably, the priorities for the operating mode requests are contained in a priority list stored in the control apparatus and can there be expanded at any time and/or changed.
In an advantageous embodiment of the invention, two operating mode requests are coupled to each other and the coupling result is further used when at least one coincidence is present in the two operating mode requests. The operating mode request having the higher priority is used as a connecting result when no coincidence is present in the two operating mode requests. Thereafter, the coupling result is coupled to the operating mode request having the next lower priority. Preferably, an AND coupling is carried out.
It is especially advantageous when each of the operating modes is assigned a priority and when that one of the available operating modes is selected which has the highest priority in the case that in the last-determined coupling result more than one operating mode is set.
Preferably, the priorities for the operating modes are contained in a priority list stored in the control apparatus and can there be supplemented and/or changed at any time.
In another embodiment of the invention, the operating mode requests and the desired operating mode are stored in the control apparatus in the form of binary data words. Each operating mode is represented by a specific bit in the binary data words.
The realization of the method of the invention is especially significant in the form of a control element which is provided for a control apparatus of an engine, especially of a motor vehicle. A program is stored on the control element which can be run on a control apparatus and especially on a microprocessor and is suitable for carrying out the method of the invention. In this case, the invention is realized by a program stored on the control element so that this control element, which is provided with the program, can define the invention in the same manner as the method for the execution of which the program is suitable. As a control element, especially an electric storage medium can be applied, for example, a read-only-memory.
Further features, possible applications and advantages of the invention will become apparent from the description of the embodiments of the invention which follows, which are shown in the figures of the drawing. All of the described or illustrated features define the invention themselves or in any desired combination thereof independently of their combination in the patent claims or their dependency as well as independently of their formulation or illustration in the description and/or in the drawing.